There is no one piece of equipment that will do it. It takes a combination of a well rounded program, combined with a good eating plan (equally, if not more important).
Looking for a specific thing to work a specific part of the body is getting off on the wrong foot. Nothing you can do will target fat loss in any particular area. The majority of the time, visible abs are not the result of too little muscle, but too much fat on top of the muscle - and no ab exercise can reduce that fat specifically.